Expandable leak path preventer in fluid activated downhole tools

ABSTRACT

Expandable seal members or inserts are included as part of fluid activated downhole tools such as packers and liner hangers. The expandable seal inserts comprise one or more expandable materials that expand and seal against the chamber carrying the actuator of the downhole tool. Fluid flowing in the downhole tool to actuate and, thus, set the downhole tool, also causes the expandable seal inserts to expand. In so doing, the expandable seal inserts provide seals, some redundant to dynamic seals and static seals already present in the downhole tool, to assist in preventing leaks in the downhole tool that may otherwise cause the downhole tool to fail.

BACKGROUND

1. Field of Invention

The present invention is directed to expandable leak path preventers foruse in downhole tools, and in particular, to expandable seal insertsdisposed in downhole tools that expand upon exposure to certain fluidsto provide leak path seals in the downhole tools.

2. Description of Art

Hydraulic set tools such as packers and liner hangers use dynamic sealson the setting pistons. These dynamic seals are often “life of the well”seals meaning that the seals must not fail, i.e., they must holddifferential pressure, during the entire life of the well.Alternatively, the dynamic seals, although not “life of the well” seals,are seals that at some point in their useful life will be subjected todifferential pressures after the downhole tool is actuated or set. Forexample, after a packer is set, a plug may be placed in the tailpipe ofthe packer for an upper end workover. In such a case, the dynamic sealsin the packer will be subjected to differential pressures that may causethe dynamic seals to fail.

In the event that the dynamic seals fail, the failed downhole tool mustbe removed and a new replacement or repaired downhole tool must berun-in and set in place of the failed downhole tool.

SUMMARY OF INVENTION

Broadly, fluid activated downhole tools such as packers and linerhangers include at least one expandable seal member or insert, formedfrom an expandable material, disposed within the actuating chamber ofthe downhole tool. The actuating chamber includes the actuator, e.g.,the setting piston. In one embodiment, the actuating chamber is in fluidcommunication with the bore of the downhole tool through a port. Asfluid, e.g., hydraulic fluid, is pumped down through the downhole toolto set the downhole tool, it travels through the port and into theactuating chamber to move the actuator and set the downhole tool. Inanother embodiment, the port provides fluid communication between theactuating chamber and the wellbore environment. In this embodiment, asfluid, e.g., wellbore fluid, is permitted access through port, such asthrough a rupture disk that breaks when the downhole tool reaches alocation having a certain pressure, to move the actuator within theactuating chamber to the set position.

In one embodiment, two expandable seal inserts are placed in theactuating chamber above and below the point where the port communicateswith the actuating chamber. As the actuator is actuated by the fluid,the expandable seal inserts begin to expand due to their contact withthe fluid. After the actuator sets the downhole tool, the expandableseal inserts continue to expand until a seal is formed over the port andthe actuator. Thus, the expandable material inserts provide a secondaryseal to the actuator's normal dynamic seals and a primary seal acrossthe port. In certain downhole tools, the expandable seal inserts mayalso provide a secondary seal to one or more dynamic seals disposedopposite the actuator that are part of the assembled downhole tool.

In one embodiment, a fluid actuated downhole tool for an oil or gas wellis disclosed. The downhole tool has a run-in position and a set positionand comprises a housing with a longitudinal bore therethrough; anactuating chamber, the actuating chamber having an actuator operativelyassociated therein for moving the downhole tool from the run-in positionto the set position; and an expandable seal insert disposed within theactuating chamber, adjacent a leak path, the expandable seal insertbeing formed from an expandable material, wherein the expandable sealinsert expands and seals the leak path when contacted with a fluid foractuating the downhole tool, the fluid causing the actuator to move thedownhole tool from the run-in position to the set position.

A further feature of the downhole tool is that the downhole tool mayfurther comprise a port in fluid communication with the actuatingchamber, wherein the expandable seal insert is disposed adjacent theport thereby causing the port to become sealed by the expandable sealinsert when the downhole tool is in the set position. Another feature ofthe downhole tool is that the port may be in fluid communication withbore. An additional feature of the downhole tool is that the actuatormay include outer and inner wall surfaces in sliding engagement withrespective outer and inner wall surfaces of the actuating chamber, theleak path including the sliding engagement between outer and inner wallsurfaces of the actuator with the respective outer and inner wallsurface of the actuating chamber, and the expandable seal insert beingdisposed adjacent the actuator thereby allowing the sliding engagementbetween outer and inner wall surfaces of the actuator with therespective outer and inner wall surface of the actuating chamber tobecome sealed by the expandable seal insert when the downhole tool is inthe set position. Still another feature of the downhole tool is that theleak path may include at least one internal dynamic seal, and whereinthe expandable seal insert is disposed adjacent at least one of the atleast one internal dynamic seals thereby allowing the at least one ofthe at least one internal dynamic seals to become sealed by theexpandable seal insert when the downhole tool is in the set position. Afurther feature of the downhole tool is that the actuator may comprise apiston in sliding engagement with the actuating chamber, the pistoncomprising at least one dynamic seal and the expandable seal insertbeing connected to the piston. Another feature of the downhole tool isthat the downhole tool may include at least two expandable seal inserts,one of the at least two expandable seal inserts being disposed adjacenta port in fluid communication with the actuating chamber and another ofthe at least two expandable seal inserts being disposed adjacent theactuator. An additional feature of the downhole tool is that theactuator may comprise a piston in sliding engagement with the actuatingchamber, the piston comprising at least one dynamic seal and theexpandable seal insert being connected to the piston. Still anotherfeature of the downhole tool is that the expandable material comprises aswellable polymer. A further feature of the downhole tool is that theexpandable seal insert may comprise an encapsulating dissolvablematerial encapsulating the expandable material prior to setting thedownhole tool. Another feature of the downhole tool is that theencapsulating material may comprise a bio-degradable polymer. Anadditional feature of the downhole tool is that the biodegradablepolymer may comprise a polyvinyl-alcohol based polymer. Still anotherfeature of the downhole tool is that the downhole tool may be a packer.

In another embodiment, an improved downhole tool has a run-in positionand a set position and is actuatable by a fluid. The improvementcomprises at least one expandable seal insert disposed along at leastone leak path, each of the at least one expandable seal inserts beingcapable of expanding and sealing at least one of the at least one leakpaths.

A further feature of the improved downhole tool is that at least one ofthe at least one expandable seal inserts may be disposed within anactuating chamber of the downhole tool. Another feature of the improveddownhole tool is that at least one of the at least one expandable sealinserts may be connected to an actuator. An additional feature of theimproved downhole tool is that at least one of the at least oneexpandable seal inserts may be disposed within an actuating chamber ofthe downhole tool adjacent a port in fluid communication with theactuating chamber. Still another feature of the improved downhole toolis that at least one of the at least one expandable seal insertscomprises a sleeve disposed within an actuating chamber of the downholetool.

In an additional embodiment, a method of preventing formation of a leakpath in an actuated downhole tool in its set position is disclosed. Themethod comprises the steps of: (a) actuating a downhole tool with afluid, wherein during actuation, the downhole tool is moved from arun-in position to a set position; (b) contacting an expandable sealinsert comprising an expandable material with the fluid causing theexpandable seal insert to expand; and (c) sealing a leak path in thedownhole tool due to the expansion of the expandable seal insert,thereby by preventing fluid leakage through the leak path with theexpanded expandable seal insert.

A further feature of the method is that the expandable seal insert maybe expanded by dissolving a dissolvable material initially disposedbetween the expandable seal insert and the fluid. Another feature of themethod is that step (b) may be performed during actuation of thedownhole tool from the run-in position to the set position. Anadditional feature of the method is that step (b) may be performed afteractuation of the downhole tool from the run-in position to the setposition.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial cross-sectional view of a packer shown in the run-inor unset position.

FIG. 2 is a partial cross-sectional view of the bottom portion of thepacker shown in FIG. 1

FIG. 3 is a partial cross-sectional view of the bottom portion of thepacker referred to in FIG. 1 shown in the set position.

While the invention will be described in connection with the preferredembodiments, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF INVENTION

Referring now to FIGS. 1-3, downhole tool 40 is a packer. Downhole tool40 comprises a longitudinal bore 44, a setting port 46 in fluidcommunication with bore 44, actuating chamber 48, and actuator 50.Actuator 50 is shown in this embodiment as a piston having dynamic seals51, 52.

Referring now to FIGS. 2-3, actuating chamber 48 includes two expandableseal inserts 60, 62, one disposed below port 46 (expandable seal insert62) and one disposed above port 46 (expandable seal insert 60). In theembodiment shown in FIGS. 1-3, expandable seal insert 60 is affixed orconnected to actuator 50 such that as actuator 50 moves from the run-inposition (FIG. 2) to the set position (FIG. 3), expandable seal insert60 moves with actuator 50. As shown in FIGS. 2-3, expandable sealinserts 60, 62 are sleeves disposed within actuating chamber 48. It isto be understood, however, the expandable seal inserts 60, 62 may haveany shape desired or necessary to seal one or more leak path aftersetting of the downhole tool.

Each expandable seal insert 60, 62 comprises, at least in part, anexpandable material that is capable of expanding and sealing against thewalls of actuating chamber 48 of downhole tool 40. In one specificembodiment, expandable seal inserts 60, 62 are formed completely out ofthe expandable material. In other embodiments, expandable seal inserts60, 62 include non-expandable components such as stiffing rings or othersupport structures or substrates to which the expandable material isconnected.

Suitable expandable materials include urethane and polyurethanematerials, including polyurethane foams, biopolymers, and superabsorbentpolymers. In one embodiment, the expandable materials swell by absorbingfluids such as water or hydrocarbons. Nitriles and polymers sold as 1064EPDM from Rubber Engineering in Salt Lake City, Utah are acceptableexpandable materials. In one embodiment, the expandable materialcomprises a swellable polymer such as cross-linked or partiallycross-linked polyacrylamide, polyurethane, ethylene propylene, or othermaterial capable of absorbing hydrocarbon or aqueous, or other fluids,and, thus, swelling to provide the desired seals. In another embodiment,the expandable material is a shape-memory material, for example, a metalshape-memory material or a compressed elastomer or polymer that is heldin the compressed state by a dissolvable material such as thosediscussed below.

In one embodiment, the expandable materials or the expandable sealinserts 60, 62 themselves may be encapsulated with a layer of materialdissolvable by fluids such as water or hydraulic fluid. As used herein,the term “encapsulated” and “encapsulating” means that the dissolvablematerial forms an initial barrier between the fluid and the expandablematerials or the expandable seal inserts 60, 62. In such embodiments,the encapsulated layer allows the use of expandable materials, andexpandable seal inserts 60, 62 formed from expandable materials, thatexpand virtually instantaneously upon contacting the fluid by protectingthe expandable materials until expansion is desired.

Encapsulating dissolvable materials for encapsulating the expandablematerials may be any material known to persons of ordinary skill in theart that can be dissolved, degraded, or disintegrated over an amount oftime by a temperature or fluid such as water-based drilling fluids,hydrocarbon-based drilling fluids, or natural gas. Preferably, theencapsulating dissolvable material is calibrated such that the amount oftime necessary for the dissolvable material to dissolve is known oreasily determinable without undue experimentation. Suitableencapsulating dissolvable materials include polymers and biodegradablepolymers, for example, polyvinyl-alcohol based polymers such as thepolymer HYDROCENE™ available from Idroplax, S.r.l. located inAltopascia, Italy, polylactide (“PLA”) polymer 4060D from Nature-Works™,a division of Cargill Dow LLC; TLF-6267 polyglycolic acid (“PGA”) fromDuPont Specialty Chemicals; polycaprolactams and mixtures of PLA andPGA; solid acids, such as sulfamic acid, trichloroacetic acid, andcitric acid, held together with a wax or other suitable binder material;polyethylene homopolymers and paraffin waxes; polyalkylene oxides, suchas polyethylene oxides, and polyalkylene glycols, such as polyethyleneglycols. These polymers may be preferred in water-based drilling fluidsbecause they are slowly soluble in water.

In one specific embodiment having an encapsulating dissolvable material,the expandable material is one or more chemical components that undergoa chemical reaction when expandable seal inserts 60, 62 are contactedwith the fluid being pumped through bore 44 and port 46 of the downholetool. For example, the expandable material may be a combination of solidparticles of magnesium oxide and monopotassium phosphate encapsulated byone or more of the above-referenced encapsulating dissolvable materials.After the dissolution of the encapsulating dissolvable material, thechemical components of the expandable material react in the presence ofthe fluid, e.g., water or hydraulic fluid, causing the chemicalcomponents to form a gel phase and, ultimately, a crystallized solidceramic material magnesium potassium phosphate hexahydrate which is achemically bonded ceramic. In such embodiments, the encapsulatingdissolvable material may also be used to separate one or more chemicalcomponent from one or more another chemical component to preventpremature reaction and expansion.

In selecting the appropriate expandable material and, if necessary ordesired the encapsulating material, for expandable seal inserts 60, 62,the amount of time necessary for actuator 50 to more from the run-inposition (FIG. 2) to the set position (FIG. 3) should be taken intoconsideration. If the expandable seal inserts 60, 62 expand prematurely,downhole tool 40 may not be completely set.

As shown in FIGS. 2-3, packer 40 includes dynamic seals 51, 52 andstatic seal 53, all of which are potential leak paths after downholetool 40 is moved to the set position (FIG. 3). Expandable seal inserts60, 62 are disposed adjacent these dynamic seals and, in the embodimentshown in FIGS. 2-3, adjacent port 46. It is to be understood, however,that expandable seal inserts 60, 62 may be disposed such that port 46,or one or more dynamic seals 51, 52 or static seal 53, do not have anexpandable seal insert disposed adjacently thereto. Moreover, one ormore expandable seal inserts may be disposed in downhole tool 40, orother downhole tools at locations other than within actuating chamber48. In other words, despite expandable seal inserts 60, 62 being showndisposed within actuating chamber 48, it is to be understood thatexpandable seal inserts 60, 62 may be disposed at any location within adownhole tool where leak paths are known to occur.

In operation, downhole tool 40 is disposed within a wellbore at thedesired location. Hydraulic fluid (not shown) is pumped down bore 44,through port 46, and into actuating chamber 48. As the pressure from thehydraulic fluid increases, actuator 50 is forced upwards causingdownhole tool 40 to move from its run-in position (FIG. 2) to its setposition (FIG. 3). In so doing, expandable seal insert 60 moves upwardwith actuator 50. The hydraulic fluid not only forces actuator 50 fromits run-in position to its set position, the hydraulic fluid also causesexpandable seal inserts 60, 62 to expand. As expandable seal inserts 60,62 expand, port 46 is blocked by expandable seal insert 62. Leak pathslocated at dynamic seals 51, 52 and static seal 53 are likewise blockedby expandable seals 60 and 62, respectively. As a result, expandableseal insert 62 provides a primary seal over port 46 and a secondary sealover static seal 53, and expandable seal insert 60 provides secondaryseals over dynamic seals 51, 52.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. For example, downhole tool 40 may be a linerhanger, or any other downhole tool or component that has a run-inposition and set position, wherein the downhole tool is moved from therun-in position to the set position using a fluid such as hydraulicfluid or other wellbore fluid. Additionally, one or more expandable sealinserts may be disposed in numerous locations throughout the downholetool to provide primary, secondary, tertiary, etc. seals when theexpandable seal inserts contact a fluid either during or after settingthe downhole tool. Further, the expandable seal inserts may becustomized based upon the size needed to provide the appropriate seal.Moreover, the expandable seal inserts may customized based upon theamount of time necessary to set the downhole tool prior to the expandingseal inserts providing the appropriate seal. Accordingly, the inventionis therefore to be limited only by the scope of the appended claims.

1. A fluid actuated downhole tool for an oil or gas well, the downholetool having a run-in position and a set position, the downhole toolcomprising: a housing with a longitudinal bore therethrough; anactuating chamber, the actuating chamber having an actuator operativelyassociated therein for moving the downhole tool from the run-in positionto the set position; and an expandable seal insert disposed within theactuating chamber, adjacent a leak path, the expandable seal insertbeing formed from an expandable material, wherein the expandable sealinsert expands and seals the leak path when contacted with a fluid foractuating the downhole tool, the fluid causing the actuator to move thedownhole tool from the run-in position to the set position.
 2. Thedownhole tool of claim 1, further comprising a port in fluidcommunication with the actuating chamber, wherein the expandable sealinsert is disposed adjacent the port thereby causing the port to becomesealed by the expandable seal insert when the downhole tool is in theset position.
 3. The downhole tool of claim 2, wherein the port is influid communication with bore.
 4. The downhole tool of claim 1, whereinthe actuator includes outer and inner wall surfaces in slidingengagement with respective outer and inner wall surfaces of theactuating chamber, the leak path including the sliding engagementbetween outer and inner wall surfaces of the actuator with therespective outer and inner wall surface of the actuating chamber, andthe expandable seal insert being disposed adjacent the actuator therebyallowing the sliding engagement between outer and inner wall surfaces ofthe actuator with the respective outer and inner wall surface of theactuating chamber to become sealed by the expandable seal insert whenthe downhole tool is in the set position.
 4. The downhole tool of claim1, wherein the leak path includes at least one internal dynamic seal,and wherein the expandable seal insert is disposed adjacent at least oneof the at least one internal dynamic seals thereby allowing the at leastone of the at least one internal dynamic seals to become sealed by theexpandable seal insert when the downhole tool is in the set position. 5.The downhole tool of claim 1, wherein the actuator comprises a piston insliding engagement with the actuating chamber, the piston comprising atleast one dynamic seal and the expandable seal insert being connected tothe piston.
 6. The downhole tool of claim 1, wherein the downhole toolincludes at least two expandable seal inserts, one of the at least twoexpandable seal inserts being disposed adjacent a port in fluidcommunication with the actuating chamber and another of the at least twoexpandable seal inserts being disposed adjacent the actuator.
 7. Thedownhole tool of claim 6, wherein the actuator comprises a piston insliding engagement with the actuating chamber, the piston comprising atleast one dynamic seal and the expandable seal insert being connected tothe piston.
 8. The downhole tool of claim 1, wherein the expandablematerial comprises a swellable polymer.
 9. The downhole tool of claim 1,wherein the expandable seal insert comprises an encapsulatingdissolvable material encapsulating the expandable material prior tosetting the downhole tool.
 10. The downhole tool of claim 9, wherein theencapsulating material comprises a bio-degradable polymer.
 11. Thedownhole tool of claim 10, wherein the bio-degradable polymer comprisesa polyvinyl-alcohol based polymer.
 12. The downhole tool of claim 1,wherein the downhole tool is a packer.
 13. An improved downhole toolhaving a run-in position and a set position, the downhole tool beingactuatable by a fluid, the improvement comprising at least oneexpandable seal insert disposed along at least one leak path, each ofthe at least one expandable seal inserts being capable of expanding andsealing at least one of the at least one leak paths.
 14. The improveddownhole tool of claim 13, wherein at least one of the at least oneexpandable seal inserts is disposed within an actuating chamber of thedownhole tool.
 15. The improved downhole tool of claim 13, wherein atleast one of the at least one expandable seal inserts is connected to anactuator.
 16. The improved downhole tool of claim 13, wherein at leastone of the at least one expandable seal inserts is disposed within anactuating chamber of the downhole tool adjacent a port in fluidcommunication with the actuating chamber.
 17. The improved downhole toolof claim 13, wherein at least one of the at least one expandable sealinserts comprises a sleeve disposed within an actuating chamber of thedownhole tool.
 18. A method of preventing formation of a leak path in anactuated downhole tool in its set position, the method comprising thesteps of: (a) actuating a downhole tool with a fluid, wherein duringactuation, the downhole tool is moved from a run-in position to a setposition; (b) contacting an expandable seal insert comprising anexpandable material with the fluid causing the expandable seal insert toexpand; and (c) sealing a leak path in the downhole tool due to theexpansion of the expandable seal insert, thereby by preventing fluidleakage through the leak path with the expanded expandable seal insert19. The method of claim 18, wherein the expandable seal insert isexpanded by dissolving a dissolvable material initially disposed betweenthe expandable seal insert and the fluid.
 20. The method of claim 18,wherein step (b) is performed during actuation of the downhole tool fromthe run-in position to the set position.
 21. The method of claim 18,wherein step (b) is performed after actuation of the downhole tool fromthe run-in position to the set position.